Open a shell at the remote end and allocate a stream for it.
sessionAn SSH connection link identifier, obtained from a call to ssh2_connect().
term_type
term_type should correspond to one of the
entries in the target system's /etc/termcap file
and defaults to vanilla.
env
env may be passed as an associative array of
name/value pairs to set in the target environment.
widthWidth of the virtual terminal.
heightHeight of the virtual terminal.
width_height_type
width_height_type should be one of
SSH2_TERM_UNIT_CHARS or
SSH2_TERM_UNIT_PIXELS.